Abstract: In 2005–2006, the National Park Service’s Northern Colorado Plateau Network received funding to develop a revised checklist of the vascular plant flora of Golden Spike National Historic Site. This entailed a thorough review of existing literature, re-examination of herbarium specimens collected from Golden Spike National Historic Site, and additional field work to corroborate unverified species reports or locate new species. Based on this study, 144 vascular plant taxa have been confirmed or reliably reported as occurring in the site (137 are known from validated herbarium specimens and 7 from unvouchered literature reports). Three species formerly considered part of the historic site flora have now been shown to be falsely reported. The current flora of Golden Spike National Historic Site represents about 4% of the known flora of Utah and 7.7% of the flora of the Great Basin ecoregion within Utah. Although no species from Golden Spike National Historic Site are listed as threatened or endangered, at least six taxa are considered species of concern by the state natural heritage program. Introduced plants make up 30.5% of the site flora (44 species), of which only two species are considered noxious weeds by the State of Utah. Further surveys in Golden Spike National Historic Site are likely to find additional new species (about 163 are known from similar habitats outside the historic site boundary), especially among late-flowering and weedy taxa. This checklist includes updates from 2011-2012.